Spectrographs

Q: Was the development of the IsoPlane motivated by your own frustration with inferior imaging spectrographs?

A: We at Princeton Instruments had been searching for methods to improve the imaging performance of the Czerny-Turner spectrograph for several years. It was only after reading a book on the aberration theory of the reflecting telescope that I happened upon the idea of the IsoPlane. I was truly motivated by the elegant treatment of image aberration in the Schmidt-Cassegrain telescope through the use of Seidel aberration theory. From this theory and some creativity, the IsoPlane SCT-320 was developed. It is named the Schmidt- Czerny-Turner (SCT) from the Schmidt-like corrector the instrument uses to help achieve its imaging performance.

Q: Do you think that spectroscopists had generally accepted that this type of spectrograph would never be invented?

A: I believe so. The commercial imaging Czerny- Turner spectrograph is roughly 30 years old and has seen little to no improvement in that time. I think many spectroscopists simply believed the design was fully mature and that no further discoveries were possible.

Q: Why has it taken so long for this product to be developed?

A: Seidel aberration theory is over 150 years old, and the Czerny-Turner spectrograph is about 80 years old. I think the reason the IsoPlane took so long to be developed was because we were all looking in the wrong place for the answers. Astronomers have hundreds more years’ experience than spectroscopists, and have fully developed Seidel aberration theory to describe every variant of the telescope. Such history does not exist for the spectrograph. We are proud to play a role in creating history with the discovery of the IsoPlane!